icexelloss commented on code in PR #35902: URL: https://github.com/apache/arrow/pull/35902#discussion_r1228577384
########## cpp/src/arrow/acero/source_node_test.cc: ########## @@ -0,0 +1,109 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you under the Apache License, Version 2.0 (the +// "License"); you may not use this file except in compliance +// with the License. You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, +// software distributed under the License is distributed on an +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +// KIND, either express or implied. See the License for the +// specific language governing permissions and limitations +// under the License. + +#include <gtest/gtest.h> + +#include "arrow/acero/exec_plan.h" +#include "arrow/acero/map_node.h" +#include "arrow/acero/options.h" +#include "arrow/acero/test_nodes.h" + +namespace arrow { +namespace acero { + +struct PauseThenStopNodeOptions : public ExecNodeOptions { + explicit PauseThenStopNodeOptions(int num_pass) : num_pass(num_pass) {} + + int num_pass; +}; + +struct PauseThenStopNode : public MapNode { + static constexpr const char* kKindName = "PauseThenStopNode"; + static constexpr const char* kFactoryName = "pause_then_stop"; + + static void Register() { + auto exec_reg = default_exec_factory_registry(); + if (!exec_reg->GetFactory(kFactoryName).ok()) { + ASSERT_OK(exec_reg->AddFactory(kFactoryName, PauseThenStopNode::Make)); + } + } + + PauseThenStopNode(ExecPlan* plan, std::vector<ExecNode*> inputs, + std::shared_ptr<Schema> output_schema, + const PauseThenStopNodeOptions& options) + : MapNode(plan, inputs, output_schema), num_pass(options.num_pass) {} + + static Result<ExecNode*> Make(ExecPlan* plan, std::vector<ExecNode*> inputs, + const ExecNodeOptions& options) { + RETURN_NOT_OK(ValidateExecNodeInputs(plan, inputs, 1, kKindName)); + auto bp_options = static_cast<const PauseThenStopNodeOptions&>(options); + if (bp_options.num_pass < 2) { + return Status::Invalid("num_pass must be at least 2"); + } + return plan->EmplaceNode<PauseThenStopNode>(plan, inputs, inputs[0]->output_schema(), + bp_options); + } + + const char* kind_name() const override { return kKindName; } + Result<ExecBatch> ProcessBatch(ExecBatch batch) override { + if (num_pass == 2) { + inputs()[0]->PauseProducing(this, 1); + } else if (num_pass == 1) { + ARROW_RETURN_NOT_OK(inputs()[0]->StopProducing()); + } + if (num_pass > 0) --num_pass; + return batch; + } + + int num_pass; +}; + +TEST(SourceNode, PauseThenStop) { + PauseThenStopNode::Register(); + + constexpr int num_pass = 2, num_batches = 10, batch_size = 1; + ASSERT_GE(num_pass, 2); + ASSERT_GT(num_batches, num_pass); + auto t_schema = schema({field("time", int32()), field("value", int32())}); + ASSERT_OK_AND_ASSIGN(auto t_batches, + MakeIntegerBatches({[](int row) -> int64_t { return row; }, + [](int row) -> int64_t { return row + 1; }}, + t_schema, num_batches, batch_size)); + + Declaration t_src = { + "source", SourceNodeOptions(t_batches.schema, + MakeDelayedGen(t_batches, "t_src", /*delay_sec=*/0.5, + /*noisy=*/false))}; + Declaration ctrl = { + PauseThenStopNode::kFactoryName, {t_src}, PauseThenStopNodeOptions(num_pass)}; + + ASSERT_OK_AND_ASSIGN(std::unique_ptr<RecordBatchReader> batch_reader, + DeclarationToReader(ctrl, /*use_threads=*/false)); + + int64_t total_length = 0; + for (;;) { + ASSERT_OK_AND_ASSIGN(auto batch, batch_reader->Next()); + if (!batch) { + break; + } + total_length += batch->num_rows(); + } + ASSERT_EQ(static_cast<int64_t>(num_pass * batch_size), total_length); Review Comment: Some more thoughts. I think we need (1) A reliable/controlled way to trigger back pressure (similar to Weston's gate node idea) (2) A way to validate that a Source node is paused because of backpresure (either via SourceNode::IsPaused()) or sth else. (i.e, in this PR https://github.com/apache/arrow/pull/35874/files#diff-dd19a151cdbe71c43bad130c0dc2d6d00db89e57b6588d1597ee0011608e3299R1476, there is a BackpresureCountingNode which seems can also serve this purpose) (3) A way to stop the execution while the query is running (either by providing an executor/thread to run the query while the main thread stop the execution, or have the main thread run the query and have a separate timed thread to stop the execution. Or just have one thread (if we manage to do this with just one thread) I agree with Weston that this test sort of works, but since we are touching back pressure/cancellation quite a bit I think it is worthwhile to improve the testing around this. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
